diff --git a/lib/importlib_resources/__init__.py b/lib/importlib_resources/__init__.py
index e6b60c18..0d029abd 100644
--- a/lib/importlib_resources/__init__.py
+++ b/lib/importlib_resources/__init__.py
@@ -4,6 +4,17 @@ from ._common import (
     as_file,
     files,
     Package,
+    Anchor,
+)
+
+from .functional import (
+    contents,
+    is_resource,
+    open_binary,
+    open_text,
+    path,
+    read_binary,
+    read_text,
 )
 
 from .abc import ResourceReader
@@ -11,7 +22,15 @@ from .abc import ResourceReader
 
 __all__ = [
     'Package',
+    'Anchor',
     'ResourceReader',
     'as_file',
     'files',
+    'contents',
+    'is_resource',
+    'open_binary',
+    'open_text',
+    'path',
+    'read_binary',
+    'read_text',
 ]
diff --git a/lib/importlib_resources/_common.py b/lib/importlib_resources/_common.py
index 3c6de1cf..8df6b39e 100644
--- a/lib/importlib_resources/_common.py
+++ b/lib/importlib_resources/_common.py
@@ -12,8 +12,6 @@ import itertools
 from typing import Union, Optional, cast
 from .abc import ResourceReader, Traversable
 
-from ._compat import wrap_spec
-
 Package = Union[types.ModuleType, str]
 Anchor = Package
 
@@ -27,6 +25,8 @@ def package_to_anchor(func):
     >>> files('a', 'b')
     Traceback (most recent call last):
     TypeError: files() takes from 0 to 1 positional arguments but 2 were given
+
+    Remove this compatibility in Python 3.14.
     """
     undefined = object()
 
@@ -109,6 +109,9 @@ def from_package(package: types.ModuleType):
     Return a Traversable object for the given package.
 
     """
+    # deferred for performance (python/cpython#109829)
+    from .future.adapters import wrap_spec
+
     spec = wrap_spec(package)
     reader = spec.loader.get_resource_reader(spec.name)
     return reader.files()
diff --git a/lib/importlib_resources/_compat.py b/lib/importlib_resources/_compat.py
deleted file mode 100644
index a93a8826..00000000
--- a/lib/importlib_resources/_compat.py
+++ /dev/null
@@ -1,109 +0,0 @@
-# flake8: noqa
-
-import abc
-import os
-import sys
-import pathlib
-from contextlib import suppress
-from typing import Union
-
-
-if sys.version_info >= (3, 10):
-    from zipfile import Path as ZipPath  # type: ignore
-else:
-    from zipp import Path as ZipPath  # type: ignore
-
-
-try:
-    from typing import runtime_checkable  # type: ignore
-except ImportError:
-
-    def runtime_checkable(cls):  # type: ignore
-        return cls
-
-
-try:
-    from typing import Protocol  # type: ignore
-except ImportError:
-    Protocol = abc.ABC  # type: ignore
-
-
-class TraversableResourcesLoader:
-    """
-    Adapt loaders to provide TraversableResources and other
-    compatibility.
-
-    Used primarily for Python 3.9 and earlier where the native
-    loaders do not yet implement TraversableResources.
-    """
-
-    def __init__(self, spec):
-        self.spec = spec
-
-    @property
-    def path(self):
-        return self.spec.origin
-
-    def get_resource_reader(self, name):
-        from . import readers, _adapters
-
-        def _zip_reader(spec):
-            with suppress(AttributeError):
-                return readers.ZipReader(spec.loader, spec.name)
-
-        def _namespace_reader(spec):
-            with suppress(AttributeError, ValueError):
-                return readers.NamespaceReader(spec.submodule_search_locations)
-
-        def _available_reader(spec):
-            with suppress(AttributeError):
-                return spec.loader.get_resource_reader(spec.name)
-
-        def _native_reader(spec):
-            reader = _available_reader(spec)
-            return reader if hasattr(reader, 'files') else None
-
-        def _file_reader(spec):
-            try:
-                path = pathlib.Path(self.path)
-            except TypeError:
-                return None
-            if path.exists():
-                return readers.FileReader(self)
-
-        return (
-            # local ZipReader if a zip module
-            _zip_reader(self.spec)
-            or
-            # local NamespaceReader if a namespace module
-            _namespace_reader(self.spec)
-            or
-            # local FileReader
-            _file_reader(self.spec)
-            or
-            # native reader if it supplies 'files'
-            _native_reader(self.spec)
-            or
-            # fallback - adapt the spec ResourceReader to TraversableReader
-            _adapters.CompatibilityFiles(self.spec)
-        )
-
-
-def wrap_spec(package):
-    """
-    Construct a package spec with traversable compatibility
-    on the spec/loader/reader.
-
-    Supersedes _adapters.wrap_spec to use TraversableResourcesLoader
-    from above for older Python compatibility (<3.10).
-    """
-    from . import _adapters
-
-    return _adapters.SpecLoaderAdapter(package.__spec__, TraversableResourcesLoader)
-
-
-if sys.version_info >= (3, 9):
-    StrPath = Union[str, os.PathLike[str]]
-else:
-    # PathLike is only subscriptable at runtime in 3.9+
-    StrPath = Union[str, "os.PathLike[str]"]
diff --git a/lib/importlib_resources/abc.py b/lib/importlib_resources/abc.py
index 23b6aeaf..7a58dd2f 100644
--- a/lib/importlib_resources/abc.py
+++ b/lib/importlib_resources/abc.py
@@ -3,8 +3,9 @@ import io
 import itertools
 import pathlib
 from typing import Any, BinaryIO, Iterable, Iterator, NoReturn, Text, Optional
+from typing import runtime_checkable, Protocol
 
-from ._compat import runtime_checkable, Protocol, StrPath
+from .compat.py38 import StrPath
 
 
 __all__ = ["ResourceReader", "Traversable", "TraversableResources"]
diff --git a/lib/importlib_resources/tests/zipdata01/__init__.py b/lib/importlib_resources/compat/__init__.py
similarity index 100%
rename from lib/importlib_resources/tests/zipdata01/__init__.py
rename to lib/importlib_resources/compat/__init__.py
diff --git a/lib/importlib_resources/compat/py38.py b/lib/importlib_resources/compat/py38.py
new file mode 100644
index 00000000..4d548257
--- /dev/null
+++ b/lib/importlib_resources/compat/py38.py
@@ -0,0 +1,11 @@
+import os
+import sys
+
+from typing import Union
+
+
+if sys.version_info >= (3, 9):
+    StrPath = Union[str, os.PathLike[str]]
+else:
+    # PathLike is only subscriptable at runtime in 3.9+
+    StrPath = Union[str, "os.PathLike[str]"]
diff --git a/lib/importlib_resources/compat/py39.py b/lib/importlib_resources/compat/py39.py
new file mode 100644
index 00000000..ab87b9dc
--- /dev/null
+++ b/lib/importlib_resources/compat/py39.py
@@ -0,0 +1,10 @@
+import sys
+
+
+__all__ = ['ZipPath']
+
+
+if sys.version_info >= (3, 10):
+    from zipfile import Path as ZipPath  # type: ignore
+else:
+    from zipp import Path as ZipPath  # type: ignore
diff --git a/lib/importlib_resources/functional.py b/lib/importlib_resources/functional.py
new file mode 100644
index 00000000..f59416f2
--- /dev/null
+++ b/lib/importlib_resources/functional.py
@@ -0,0 +1,81 @@
+"""Simplified function-based API for importlib.resources"""
+
+import warnings
+
+from ._common import files, as_file
+
+
+_MISSING = object()
+
+
+def open_binary(anchor, *path_names):
+    """Open for binary reading the *resource* within *package*."""
+    return _get_resource(anchor, path_names).open('rb')
+
+
+def open_text(anchor, *path_names, encoding=_MISSING, errors='strict'):
+    """Open for text reading the *resource* within *package*."""
+    encoding = _get_encoding_arg(path_names, encoding)
+    resource = _get_resource(anchor, path_names)
+    return resource.open('r', encoding=encoding, errors=errors)
+
+
+def read_binary(anchor, *path_names):
+    """Read and return contents of *resource* within *package* as bytes."""
+    return _get_resource(anchor, path_names).read_bytes()
+
+
+def read_text(anchor, *path_names, encoding=_MISSING, errors='strict'):
+    """Read and return contents of *resource* within *package* as str."""
+    encoding = _get_encoding_arg(path_names, encoding)
+    resource = _get_resource(anchor, path_names)
+    return resource.read_text(encoding=encoding, errors=errors)
+
+
+def path(anchor, *path_names):
+    """Return the path to the *resource* as an actual file system path."""
+    return as_file(_get_resource(anchor, path_names))
+
+
+def is_resource(anchor, *path_names):
+    """Return ``True`` if there is a resource named *name* in the package,
+
+    Otherwise returns ``False``.
+    """
+    return _get_resource(anchor, path_names).is_file()
+
+
+def contents(anchor, *path_names):
+    """Return an iterable over the named resources within the package.
+
+    The iterable returns :class:`str` resources (e.g. files).
+    The iterable does not recurse into subdirectories.
+    """
+    warnings.warn(
+        "importlib.resources.contents is deprecated. "
+        "Use files(anchor).iterdir() instead.",
+        DeprecationWarning,
+        stacklevel=1,
+    )
+    return (resource.name for resource in _get_resource(anchor, path_names).iterdir())
+
+
+def _get_encoding_arg(path_names, encoding):
+    # For compatibility with versions where *encoding* was a positional
+    # argument, it needs to be given explicitly when there are multiple
+    # *path_names*.
+    # This limitation can be removed in Python 3.15.
+    if encoding is _MISSING:
+        if len(path_names) > 1:
+            raise TypeError(
+                "'encoding' argument required with multiple path names",
+            )
+        else:
+            return 'utf-8'
+    return encoding
+
+
+def _get_resource(anchor, path_names):
+    if anchor is None:
+        raise TypeError("anchor must be module or string, got None")
+    return files(anchor).joinpath(*path_names)
diff --git a/lib/importlib_resources/tests/zipdata02/__init__.py b/lib/importlib_resources/future/__init__.py
similarity index 100%
rename from lib/importlib_resources/tests/zipdata02/__init__.py
rename to lib/importlib_resources/future/__init__.py
diff --git a/lib/importlib_resources/future/adapters.py b/lib/importlib_resources/future/adapters.py
new file mode 100644
index 00000000..0e9764ba
--- /dev/null
+++ b/lib/importlib_resources/future/adapters.py
@@ -0,0 +1,95 @@
+import functools
+import pathlib
+from contextlib import suppress
+from types import SimpleNamespace
+
+from .. import readers, _adapters
+
+
+def _block_standard(reader_getter):
+    """
+    Wrap _adapters.TraversableResourcesLoader.get_resource_reader
+    and intercept any standard library readers.
+    """
+
+    @functools.wraps(reader_getter)
+    def wrapper(*args, **kwargs):
+        """
+        If the reader is from the standard library, return None to allow
+        allow likely newer implementations in this library to take precedence.
+        """
+        try:
+            reader = reader_getter(*args, **kwargs)
+        except NotADirectoryError:
+            # MultiplexedPath may fail on zip subdirectory
+            return
+        # Python 3.10+
+        mod_name = reader.__class__.__module__
+        if mod_name.startswith('importlib.') and mod_name.endswith('readers'):
+            return
+        # Python 3.8, 3.9
+        if isinstance(reader, _adapters.CompatibilityFiles) and (
+            reader.spec.loader.__class__.__module__.startswith('zipimport')
+            or reader.spec.loader.__class__.__module__.startswith(
+                '_frozen_importlib_external'
+            )
+        ):
+            return
+        return reader
+
+    return wrapper
+
+
+def _skip_degenerate(reader):
+    """
+    Mask any degenerate reader. Ref #298.
+    """
+    is_degenerate = (
+        isinstance(reader, _adapters.CompatibilityFiles) and not reader._reader
+    )
+    return reader if not is_degenerate else None
+
+
+class TraversableResourcesLoader(_adapters.TraversableResourcesLoader):
+    """
+    Adapt loaders to provide TraversableResources and other
+    compatibility.
+
+    Ensures the readers from importlib_resources are preferred
+    over stdlib readers.
+    """
+
+    def get_resource_reader(self, name):
+        return (
+            _skip_degenerate(_block_standard(super().get_resource_reader)(name))
+            or self._standard_reader()
+            or super().get_resource_reader(name)
+        )
+
+    def _standard_reader(self):
+        return self._zip_reader() or self._namespace_reader() or self._file_reader()
+
+    def _zip_reader(self):
+        with suppress(AttributeError):
+            return readers.ZipReader(self.spec.loader, self.spec.name)
+
+    def _namespace_reader(self):
+        with suppress(AttributeError, ValueError):
+            return readers.NamespaceReader(self.spec.submodule_search_locations)
+
+    def _file_reader(self):
+        try:
+            path = pathlib.Path(self.spec.origin)
+        except TypeError:
+            return None
+        if path.exists():
+            return readers.FileReader(SimpleNamespace(path=path))
+
+
+def wrap_spec(package):
+    """
+    Override _adapters.wrap_spec to use TraversableResourcesLoader
+    from above. Ensures that future behavior is always available on older
+    Pythons.
+    """
+    return _adapters.SpecLoaderAdapter(package.__spec__, TraversableResourcesLoader)
diff --git a/lib/importlib_resources/readers.py b/lib/importlib_resources/readers.py
index 51d030a6..4a80a774 100644
--- a/lib/importlib_resources/readers.py
+++ b/lib/importlib_resources/readers.py
@@ -1,12 +1,15 @@
 import collections
+import contextlib
 import itertools
 import pathlib
 import operator
+import re
+import warnings
 
 from . import abc
 
 from ._itertools import only
-from ._compat import ZipPath
+from .compat.py39 import ZipPath
 
 
 def remove_duplicates(items):
@@ -62,7 +65,7 @@ class MultiplexedPath(abc.Traversable):
     """
 
     def __init__(self, *paths):
-        self._paths = list(map(pathlib.Path, remove_duplicates(paths)))
+        self._paths = list(map(_ensure_traversable, remove_duplicates(paths)))
         if not self._paths:
             message = 'MultiplexedPath must contain at least one path'
             raise FileNotFoundError(message)
@@ -130,7 +133,36 @@ class NamespaceReader(abc.TraversableResources):
     def __init__(self, namespace_path):
         if 'NamespacePath' not in str(namespace_path):
             raise ValueError('Invalid path')
-        self.path = MultiplexedPath(*list(namespace_path))
+        self.path = MultiplexedPath(*map(self._resolve, namespace_path))
+
+    @classmethod
+    def _resolve(cls, path_str) -> abc.Traversable:
+        r"""
+        Given an item from a namespace path, resolve it to a Traversable.
+
+        path_str might be a directory on the filesystem or a path to a
+        zipfile plus the path within the zipfile, e.g. ``/foo/bar`` or
+        ``/foo/baz.zip/inner_dir`` or ``foo\baz.zip\inner_dir\sub``.
+        """
+        (dir,) = (cand for cand in cls._candidate_paths(path_str) if cand.is_dir())
+        return dir
+
+    @classmethod
+    def _candidate_paths(cls, path_str):
+        yield pathlib.Path(path_str)
+        yield from cls._resolve_zip_path(path_str)
+
+    @staticmethod
+    def _resolve_zip_path(path_str):
+        for match in reversed(list(re.finditer(r'[\\/]', path_str))):
+            with contextlib.suppress(
+                FileNotFoundError,
+                IsADirectoryError,
+                NotADirectoryError,
+                PermissionError,
+            ):
+                inner = path_str[match.end() :].replace('\\', '/') + '/'
+                yield ZipPath(path_str[: match.start()], inner.lstrip('/'))
 
     def resource_path(self, resource):
         """
@@ -142,3 +174,21 @@ class NamespaceReader(abc.TraversableResources):
 
     def files(self):
         return self.path
+
+
+def _ensure_traversable(path):
+    """
+    Convert deprecated string arguments to traversables (pathlib.Path).
+
+    Remove with Python 3.15.
+    """
+    if not isinstance(path, str):
+        return path
+
+    warnings.warn(
+        "String arguments are deprecated. Pass a Traversable instead.",
+        DeprecationWarning,
+        stacklevel=3,
+    )
+
+    return pathlib.Path(path)
diff --git a/lib/importlib_resources/simple.py b/lib/importlib_resources/simple.py
index 7770c922..96f117fe 100644
--- a/lib/importlib_resources/simple.py
+++ b/lib/importlib_resources/simple.py
@@ -88,7 +88,7 @@ class ResourceHandle(Traversable):
     def open(self, mode='r', *args, **kwargs):
         stream = self.parent.reader.open_binary(self.name)
         if 'b' not in mode:
-            stream = io.TextIOWrapper(*args, **kwargs)
+            stream = io.TextIOWrapper(stream, *args, **kwargs)
         return stream
 
     def joinpath(self, name):
diff --git a/lib/importlib_resources/tests/_compat.py b/lib/importlib_resources/tests/_compat.py
deleted file mode 100644
index e7bf06dd..00000000
--- a/lib/importlib_resources/tests/_compat.py
+++ /dev/null
@@ -1,32 +0,0 @@
-import os
-
-
-try:
-    from test.support import import_helper  # type: ignore
-except ImportError:
-    # Python 3.9 and earlier
-    class import_helper:  # type: ignore
-        from test.support import (
-            modules_setup,
-            modules_cleanup,
-            DirsOnSysPath,
-            CleanImport,
-        )
-
-
-try:
-    from test.support import os_helper  # type: ignore
-except ImportError:
-    # Python 3.9 compat
-    class os_helper:  # type:ignore
-        from test.support import temp_dir
-
-
-try:
-    # Python 3.10
-    from test.support.os_helper import unlink
-except ImportError:
-    from test.support import unlink as _unlink
-
-    def unlink(target):
-        return _unlink(os.fspath(target))
diff --git a/lib/importlib_resources/tests/compat/__init__.py b/lib/importlib_resources/tests/compat/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/lib/importlib_resources/tests/compat/py312.py b/lib/importlib_resources/tests/compat/py312.py
new file mode 100644
index 00000000..ea9a58ba
--- /dev/null
+++ b/lib/importlib_resources/tests/compat/py312.py
@@ -0,0 +1,18 @@
+import contextlib
+
+from .py39 import import_helper
+
+
+@contextlib.contextmanager
+def isolated_modules():
+    """
+    Save modules on entry and cleanup on exit.
+    """
+    (saved,) = import_helper.modules_setup()
+    try:
+        yield
+    finally:
+        import_helper.modules_cleanup(saved)
+
+
+vars(import_helper).setdefault('isolated_modules', isolated_modules)
diff --git a/lib/importlib_resources/tests/compat/py39.py b/lib/importlib_resources/tests/compat/py39.py
new file mode 100644
index 00000000..e158eb85
--- /dev/null
+++ b/lib/importlib_resources/tests/compat/py39.py
@@ -0,0 +1,10 @@
+"""
+Backward-compatability shims to support Python 3.9 and earlier.
+"""
+
+from jaraco.test.cpython import from_test_support, try_import
+
+import_helper = try_import('import_helper') or from_test_support(
+    'modules_setup', 'modules_cleanup', 'DirsOnSysPath'
+)
+os_helper = try_import('os_helper') or from_test_support('temp_dir')
diff --git a/lib/importlib_resources/tests/data01/subdirectory/binary.file b/lib/importlib_resources/tests/data01/subdirectory/binary.file
index eaf36c1d..5bd8bb89 100644
Binary files a/lib/importlib_resources/tests/data01/subdirectory/binary.file and b/lib/importlib_resources/tests/data01/subdirectory/binary.file differ
diff --git a/lib/importlib_resources/tests/namespacedata01/subdirectory/binary.file b/lib/importlib_resources/tests/namespacedata01/subdirectory/binary.file
new file mode 100644
index 00000000..100f5064
--- /dev/null
+++ b/lib/importlib_resources/tests/namespacedata01/subdirectory/binary.file
@@ -0,0 +1 @@
+

\ No newline at end of file
diff --git a/lib/importlib_resources/tests/test_contents.py b/lib/importlib_resources/tests/test_contents.py
index 525568e8..7dc3b0a6 100644
--- a/lib/importlib_resources/tests/test_contents.py
+++ b/lib/importlib_resources/tests/test_contents.py
@@ -31,8 +31,8 @@ class ContentsZipTests(ContentsTests, util.ZipSetup, unittest.TestCase):
 class ContentsNamespaceTests(ContentsTests, unittest.TestCase):
     expected = {
         # no __init__ because of namespace design
-        # no subdirectory as incidental difference in fixture
         'binary.file',
+        'subdirectory',
         'utf-16.file',
         'utf-8.file',
     }
diff --git a/lib/importlib_resources/tests/test_custom.py b/lib/importlib_resources/tests/test_custom.py
index e85ddd65..86c65676 100644
--- a/lib/importlib_resources/tests/test_custom.py
+++ b/lib/importlib_resources/tests/test_custom.py
@@ -3,9 +3,10 @@ import contextlib
 import pathlib
 
 import importlib_resources as resources
+from .. import abc
 from ..abc import TraversableResources, ResourceReader
 from . import util
-from ._compat import os_helper
+from .compat.py39 import os_helper
 
 
 class SimpleLoader:
@@ -38,8 +39,9 @@ class CustomTraversableResourcesTests(unittest.TestCase):
         self.addCleanup(self.fixtures.close)
 
     def test_custom_loader(self):
-        temp_dir = self.fixtures.enter_context(os_helper.temp_dir())
+        temp_dir = pathlib.Path(self.fixtures.enter_context(os_helper.temp_dir()))
         loader = SimpleLoader(MagicResources(temp_dir))
         pkg = util.create_package_from_loader(loader)
         files = resources.files(pkg)
-        assert files is temp_dir
+        assert isinstance(files, abc.Traversable)
+        assert list(files.iterdir()) == []
diff --git a/lib/importlib_resources/tests/test_files.py b/lib/importlib_resources/tests/test_files.py
index 197a063b..3e86ec64 100644
--- a/lib/importlib_resources/tests/test_files.py
+++ b/lib/importlib_resources/tests/test_files.py
@@ -1,4 +1,3 @@
-import typing
 import textwrap
 import unittest
 import warnings
@@ -10,7 +9,8 @@ from ..abc import Traversable
 from . import data01
 from . import util
 from . import _path
-from ._compat import os_helper, import_helper
+from .compat.py39 import os_helper
+from .compat.py312 import import_helper
 
 
 @contextlib.contextmanager
@@ -31,13 +31,14 @@ class FilesTests:
         actual = files.joinpath('utf-8.file').read_text(encoding='utf-8')
         assert actual == 'Hello, UTF-8 world!\n'
 
-    @unittest.skipUnless(
-        hasattr(typing, 'runtime_checkable'),
-        "Only suitable when typing supports runtime_checkable",
-    )
     def test_traversable(self):
         assert isinstance(resources.files(self.data), Traversable)
 
+    def test_joinpath_with_multiple_args(self):
+        files = resources.files(self.data)
+        binfile = files.joinpath('subdirectory', 'binary.file')
+        self.assertTrue(binfile.is_file())
+
     def test_old_parameter(self):
         """
         Files used to take a 'package' parameter. Make sure anyone
@@ -63,13 +64,17 @@ class OpenNamespaceTests(FilesTests, unittest.TestCase):
         self.data = namespacedata01
 
 
+class OpenNamespaceZipTests(FilesTests, util.ZipSetup, unittest.TestCase):
+    ZIP_MODULE = 'namespacedata01'
+
+
 class SiteDir:
     def setUp(self):
         self.fixtures = contextlib.ExitStack()
         self.addCleanup(self.fixtures.close)
         self.site_dir = self.fixtures.enter_context(os_helper.temp_dir())
         self.fixtures.enter_context(import_helper.DirsOnSysPath(self.site_dir))
-        self.fixtures.enter_context(import_helper.CleanImport())
+        self.fixtures.enter_context(import_helper.isolated_modules())
 
 
 class ModulesFilesTests(SiteDir, unittest.TestCase):
diff --git a/lib/importlib_resources/tests/test_functional.py b/lib/importlib_resources/tests/test_functional.py
new file mode 100644
index 00000000..69706cf7
--- /dev/null
+++ b/lib/importlib_resources/tests/test_functional.py
@@ -0,0 +1,242 @@
+import unittest
+import os
+import contextlib
+
+try:
+    from test.support.warnings_helper import ignore_warnings, check_warnings
+except ImportError:
+    # older Python versions
+    from test.support import ignore_warnings, check_warnings
+
+import importlib_resources as resources
+
+# Since the functional API forwards to Traversable, we only test
+# filesystem resources here -- not zip files, namespace packages etc.
+# We do test for two kinds of Anchor, though.
+
+
+class StringAnchorMixin:
+    anchor01 = 'importlib_resources.tests.data01'
+    anchor02 = 'importlib_resources.tests.data02'
+
+
+class ModuleAnchorMixin:
+    from . import data01 as anchor01
+    from . import data02 as anchor02
+
+
+class FunctionalAPIBase:
+    def _gen_resourcetxt_path_parts(self):
+        """Yield various names of a text file in anchor02, each in a subTest"""
+        for path_parts in (
+            ('subdirectory', 'subsubdir', 'resource.txt'),
+            ('subdirectory/subsubdir/resource.txt',),
+            ('subdirectory/subsubdir', 'resource.txt'),
+        ):
+            with self.subTest(path_parts=path_parts):
+                yield path_parts
+
+    def test_read_text(self):
+        self.assertEqual(
+            resources.read_text(self.anchor01, 'utf-8.file'),
+            'Hello, UTF-8 world!\n',
+        )
+        self.assertEqual(
+            resources.read_text(
+                self.anchor02,
+                'subdirectory',
+                'subsubdir',
+                'resource.txt',
+                encoding='utf-8',
+            ),
+            'a resource',
+        )
+        for path_parts in self._gen_resourcetxt_path_parts():
+            self.assertEqual(
+                resources.read_text(
+                    self.anchor02,
+                    *path_parts,
+                    encoding='utf-8',
+                ),
+                'a resource',
+            )
+        # Use generic OSError, since e.g. attempting to read a directory can
+        # fail with PermissionError rather than IsADirectoryError
+        with self.assertRaises(OSError):
+            resources.read_text(self.anchor01)
+        with self.assertRaises(OSError):
+            resources.read_text(self.anchor01, 'no-such-file')
+        with self.assertRaises(UnicodeDecodeError):
+            resources.read_text(self.anchor01, 'utf-16.file')
+        self.assertEqual(
+            resources.read_text(
+                self.anchor01,
+                'binary.file',
+                encoding='latin1',
+            ),
+            '\x00\x01\x02\x03',
+        )
+        self.assertEqual(
+            resources.read_text(
+                self.anchor01,
+                'utf-16.file',
+                errors='backslashreplace',
+            ),
+            'Hello, UTF-16 world!\n'.encode('utf-16').decode(
+                errors='backslashreplace',
+            ),
+        )
+
+    def test_read_binary(self):
+        self.assertEqual(
+            resources.read_binary(self.anchor01, 'utf-8.file'),
+            b'Hello, UTF-8 world!\n',
+        )
+        for path_parts in self._gen_resourcetxt_path_parts():
+            self.assertEqual(
+                resources.read_binary(self.anchor02, *path_parts),
+                b'a resource',
+            )
+
+    def test_open_text(self):
+        with resources.open_text(self.anchor01, 'utf-8.file') as f:
+            self.assertEqual(f.read(), 'Hello, UTF-8 world!\n')
+        for path_parts in self._gen_resourcetxt_path_parts():
+            with resources.open_text(
+                self.anchor02,
+                *path_parts,
+                encoding='utf-8',
+            ) as f:
+                self.assertEqual(f.read(), 'a resource')
+        # Use generic OSError, since e.g. attempting to read a directory can
+        # fail with PermissionError rather than IsADirectoryError
+        with self.assertRaises(OSError):
+            resources.open_text(self.anchor01)
+        with self.assertRaises(OSError):
+            resources.open_text(self.anchor01, 'no-such-file')
+        with resources.open_text(self.anchor01, 'utf-16.file') as f:
+            with self.assertRaises(UnicodeDecodeError):
+                f.read()
+        with resources.open_text(
+            self.anchor01,
+            'binary.file',
+            encoding='latin1',
+        ) as f:
+            self.assertEqual(f.read(), '\x00\x01\x02\x03')
+        with resources.open_text(
+            self.anchor01,
+            'utf-16.file',
+            errors='backslashreplace',
+        ) as f:
+            self.assertEqual(
+                f.read(),
+                'Hello, UTF-16 world!\n'.encode('utf-16').decode(
+                    errors='backslashreplace',
+                ),
+            )
+
+    def test_open_binary(self):
+        with resources.open_binary(self.anchor01, 'utf-8.file') as f:
+            self.assertEqual(f.read(), b'Hello, UTF-8 world!\n')
+        for path_parts in self._gen_resourcetxt_path_parts():
+            with resources.open_binary(
+                self.anchor02,
+                *path_parts,
+            ) as f:
+                self.assertEqual(f.read(), b'a resource')
+
+    def test_path(self):
+        with resources.path(self.anchor01, 'utf-8.file') as path:
+            with open(str(path), encoding='utf-8') as f:
+                self.assertEqual(f.read(), 'Hello, UTF-8 world!\n')
+        with resources.path(self.anchor01) as path:
+            with open(os.path.join(path, 'utf-8.file'), encoding='utf-8') as f:
+                self.assertEqual(f.read(), 'Hello, UTF-8 world!\n')
+
+    def test_is_resource(self):
+        is_resource = resources.is_resource
+        self.assertTrue(is_resource(self.anchor01, 'utf-8.file'))
+        self.assertFalse(is_resource(self.anchor01, 'no_such_file'))
+        self.assertFalse(is_resource(self.anchor01))
+        self.assertFalse(is_resource(self.anchor01, 'subdirectory'))
+        for path_parts in self._gen_resourcetxt_path_parts():
+            self.assertTrue(is_resource(self.anchor02, *path_parts))
+
+    def test_contents(self):
+        with check_warnings((".*contents.*", DeprecationWarning)):
+            c = resources.contents(self.anchor01)
+        self.assertGreaterEqual(
+            set(c),
+            {'utf-8.file', 'utf-16.file', 'binary.file', 'subdirectory'},
+        )
+        with contextlib.ExitStack() as cm:
+            cm.enter_context(self.assertRaises(OSError))
+            cm.enter_context(check_warnings((".*contents.*", DeprecationWarning)))
+
+            list(resources.contents(self.anchor01, 'utf-8.file'))
+
+        for path_parts in self._gen_resourcetxt_path_parts():
+            with contextlib.ExitStack() as cm:
+                cm.enter_context(self.assertRaises(OSError))
+                cm.enter_context(check_warnings((".*contents.*", DeprecationWarning)))
+
+                list(resources.contents(self.anchor01, *path_parts))
+        with check_warnings((".*contents.*", DeprecationWarning)):
+            c = resources.contents(self.anchor01, 'subdirectory')
+        self.assertGreaterEqual(
+            set(c),
+            {'binary.file'},
+        )
+
+    @ignore_warnings(category=DeprecationWarning)
+    def test_common_errors(self):
+        for func in (
+            resources.read_text,
+            resources.read_binary,
+            resources.open_text,
+            resources.open_binary,
+            resources.path,
+            resources.is_resource,
+            resources.contents,
+        ):
+            with self.subTest(func=func):
+                # Rejecting None anchor
+                with self.assertRaises(TypeError):
+                    func(None)
+                # Rejecting invalid anchor type
+                with self.assertRaises((TypeError, AttributeError)):
+                    func(1234)
+                # Unknown module
+                with self.assertRaises(ModuleNotFoundError):
+                    func('$missing module$')
+
+    def test_text_errors(self):
+        for func in (
+            resources.read_text,
+            resources.open_text,
+        ):
+            with self.subTest(func=func):
+                # Multiple path arguments need explicit encoding argument.
+                with self.assertRaises(TypeError):
+                    func(
+                        self.anchor02,
+                        'subdirectory',
+                        'subsubdir',
+                        'resource.txt',
+                    )
+
+
+class FunctionalAPITest_StringAnchor(
+    unittest.TestCase,
+    FunctionalAPIBase,
+    StringAnchorMixin,
+):
+    pass
+
+
+class FunctionalAPITest_ModuleAnchor(
+    unittest.TestCase,
+    FunctionalAPIBase,
+    ModuleAnchorMixin,
+):
+    pass
diff --git a/lib/importlib_resources/tests/test_open.py b/lib/importlib_resources/tests/test_open.py
index 83b737dc..44f1018a 100644
--- a/lib/importlib_resources/tests/test_open.py
+++ b/lib/importlib_resources/tests/test_open.py
@@ -24,7 +24,7 @@ class OpenTests:
         target = resources.files(self.data) / 'binary.file'
         with target.open('rb') as fp:
             result = fp.read()
-            self.assertEqual(result, b'\x00\x01\x02\x03')
+            self.assertEqual(result, bytes(range(4)))
 
     def test_open_text_default_encoding(self):
         target = resources.files(self.data) / 'utf-8.file'
@@ -81,5 +81,9 @@ class OpenZipTests(OpenTests, util.ZipSetup, unittest.TestCase):
     pass
 
 
+class OpenNamespaceZipTests(OpenTests, util.ZipSetup, unittest.TestCase):
+    ZIP_MODULE = 'namespacedata01'
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/lib/importlib_resources/tests/test_path.py b/lib/importlib_resources/tests/test_path.py
index 7cb20003..c3e1cbb4 100644
--- a/lib/importlib_resources/tests/test_path.py
+++ b/lib/importlib_resources/tests/test_path.py
@@ -1,4 +1,5 @@
 import io
+import pathlib
 import unittest
 
 import importlib_resources as resources
@@ -15,18 +16,13 @@ class CommonTests(util.CommonTests, unittest.TestCase):
 class PathTests:
     def test_reading(self):
         """
-        Path should be readable.
-
-        Test also implicitly verifies the returned object is a pathlib.Path
-        instance.
+        Path should be readable and a pathlib.Path instance.
         """
         target = resources.files(self.data) / 'utf-8.file'
         with resources.as_file(target) as path:
+            self.assertIsInstance(path, pathlib.Path)
             self.assertTrue(path.name.endswith("utf-8.file"), repr(path))
-            # pathlib.Path.read_text() was introduced in Python 3.5.
-            with path.open('r', encoding='utf-8') as file:
-                text = file.read()
-            self.assertEqual('Hello, UTF-8 world!\n', text)
+            self.assertEqual('Hello, UTF-8 world!\n', path.read_text(encoding='utf-8'))
 
 
 class PathDiskTests(PathTests, unittest.TestCase):
diff --git a/lib/importlib_resources/tests/test_read.py b/lib/importlib_resources/tests/test_read.py
index b5aaec45..97d90128 100644
--- a/lib/importlib_resources/tests/test_read.py
+++ b/lib/importlib_resources/tests/test_read.py
@@ -19,7 +19,7 @@ class CommonTextTests(util.CommonTests, unittest.TestCase):
 class ReadTests:
     def test_read_bytes(self):
         result = resources.files(self.data).joinpath('binary.file').read_bytes()
-        self.assertEqual(result, b'\0\1\2\3')
+        self.assertEqual(result, bytes(range(4)))
 
     def test_read_text_default_encoding(self):
         result = (
@@ -58,17 +58,15 @@ class ReadDiskTests(ReadTests, unittest.TestCase):
 
 class ReadZipTests(ReadTests, util.ZipSetup, unittest.TestCase):
     def test_read_submodule_resource(self):
-        submodule = import_module('ziptestdata.subdirectory')
+        submodule = import_module('data01.subdirectory')
         result = resources.files(submodule).joinpath('binary.file').read_bytes()
-        self.assertEqual(result, b'\0\1\2\3')
+        self.assertEqual(result, bytes(range(4, 8)))
 
     def test_read_submodule_resource_by_name(self):
         result = (
-            resources.files('ziptestdata.subdirectory')
-            .joinpath('binary.file')
-            .read_bytes()
+            resources.files('data01.subdirectory').joinpath('binary.file').read_bytes()
         )
-        self.assertEqual(result, b'\0\1\2\3')
+        self.assertEqual(result, bytes(range(4, 8)))
 
 
 class ReadNamespaceTests(ReadTests, unittest.TestCase):
@@ -78,5 +76,22 @@ class ReadNamespaceTests(ReadTests, unittest.TestCase):
         self.data = namespacedata01
 
 
+class ReadNamespaceZipTests(ReadTests, util.ZipSetup, unittest.TestCase):
+    ZIP_MODULE = 'namespacedata01'
+
+    def test_read_submodule_resource(self):
+        submodule = import_module('namespacedata01.subdirectory')
+        result = resources.files(submodule).joinpath('binary.file').read_bytes()
+        self.assertEqual(result, bytes(range(12, 16)))
+
+    def test_read_submodule_resource_by_name(self):
+        result = (
+            resources.files('namespacedata01.subdirectory')
+            .joinpath('binary.file')
+            .read_bytes()
+        )
+        self.assertEqual(result, bytes(range(12, 16)))
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/lib/importlib_resources/tests/test_reader.py b/lib/importlib_resources/tests/test_reader.py
index e2bdf19c..95c2fc85 100644
--- a/lib/importlib_resources/tests/test_reader.py
+++ b/lib/importlib_resources/tests/test_reader.py
@@ -10,8 +10,7 @@ from importlib_resources.readers import MultiplexedPath, NamespaceReader
 class MultiplexedPathTest(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
-        path = pathlib.Path(__file__).parent / 'namespacedata01'
-        cls.folder = str(path)
+        cls.folder = pathlib.Path(__file__).parent / 'namespacedata01'
 
     def test_init_no_paths(self):
         with self.assertRaises(FileNotFoundError):
@@ -19,7 +18,7 @@ class MultiplexedPathTest(unittest.TestCase):
 
     def test_init_file(self):
         with self.assertRaises(NotADirectoryError):
-            MultiplexedPath(os.path.join(self.folder, 'binary.file'))
+            MultiplexedPath(self.folder / 'binary.file')
 
     def test_iterdir(self):
         contents = {path.name for path in MultiplexedPath(self.folder).iterdir()}
@@ -27,10 +26,12 @@ class MultiplexedPathTest(unittest.TestCase):
             contents.remove('__pycache__')
         except (KeyError, ValueError):
             pass
-        self.assertEqual(contents, {'binary.file', 'utf-16.file', 'utf-8.file'})
+        self.assertEqual(
+            contents, {'subdirectory', 'binary.file', 'utf-16.file', 'utf-8.file'}
+        )
 
     def test_iterdir_duplicate(self):
-        data01 = os.path.abspath(os.path.join(__file__, '..', 'data01'))
+        data01 = pathlib.Path(__file__).parent.joinpath('data01')
         contents = {
             path.name for path in MultiplexedPath(self.folder, data01).iterdir()
         }
@@ -60,17 +61,17 @@ class MultiplexedPathTest(unittest.TestCase):
             path.open()
 
     def test_join_path(self):
-        prefix = os.path.abspath(os.path.join(__file__, '..'))
-        data01 = os.path.join(prefix, 'data01')
+        data01 = pathlib.Path(__file__).parent.joinpath('data01')
+        prefix = str(data01.parent)
         path = MultiplexedPath(self.folder, data01)
         self.assertEqual(
             str(path.joinpath('binary.file'))[len(prefix) + 1 :],
             os.path.join('namespacedata01', 'binary.file'),
         )
-        self.assertEqual(
-            str(path.joinpath('subdirectory'))[len(prefix) + 1 :],
-            os.path.join('data01', 'subdirectory'),
-        )
+        sub = path.joinpath('subdirectory')
+        assert isinstance(sub, MultiplexedPath)
+        assert 'namespacedata01' in str(sub)
+        assert 'data01' in str(sub)
         self.assertEqual(
             str(path.joinpath('imaginary'))[len(prefix) + 1 :],
             os.path.join('namespacedata01', 'imaginary'),
@@ -82,9 +83,9 @@ class MultiplexedPathTest(unittest.TestCase):
         assert not path.joinpath('imaginary/foo.py').exists()
 
     def test_join_path_common_subdir(self):
-        prefix = os.path.abspath(os.path.join(__file__, '..'))
-        data01 = os.path.join(prefix, 'data01')
-        data02 = os.path.join(prefix, 'data02')
+        data01 = pathlib.Path(__file__).parent.joinpath('data01')
+        data02 = pathlib.Path(__file__).parent.joinpath('data02')
+        prefix = str(data01.parent)
         path = MultiplexedPath(data01, data02)
         self.assertIsInstance(path.joinpath('subdirectory'), MultiplexedPath)
         self.assertEqual(
diff --git a/lib/importlib_resources/tests/test_resource.py b/lib/importlib_resources/tests/test_resource.py
index 677110cd..dc2a108c 100644
--- a/lib/importlib_resources/tests/test_resource.py
+++ b/lib/importlib_resources/tests/test_resource.py
@@ -1,15 +1,11 @@
-import contextlib
 import sys
 import unittest
 import importlib_resources as resources
-import uuid
 import pathlib
 
 from . import data01
-from . import zipdata01, zipdata02
 from . import util
 from importlib import import_module
-from ._compat import import_helper, os_helper, unlink
 
 
 class ResourceTests:
@@ -89,34 +85,32 @@ class ResourceCornerCaseTests(unittest.TestCase):
 
 
 class ResourceFromZipsTest01(util.ZipSetupBase, unittest.TestCase):
-    ZIP_MODULE = zipdata01  # type: ignore
+    ZIP_MODULE = 'data01'
 
     def test_is_submodule_resource(self):
-        submodule = import_module('ziptestdata.subdirectory')
+        submodule = import_module('data01.subdirectory')
         self.assertTrue(resources.files(submodule).joinpath('binary.file').is_file())
 
     def test_read_submodule_resource_by_name(self):
         self.assertTrue(
-            resources.files('ziptestdata.subdirectory')
-            .joinpath('binary.file')
-            .is_file()
+            resources.files('data01.subdirectory').joinpath('binary.file').is_file()
         )
 
     def test_submodule_contents(self):
-        submodule = import_module('ziptestdata.subdirectory')
+        submodule = import_module('data01.subdirectory')
         self.assertEqual(
             names(resources.files(submodule)), {'__init__.py', 'binary.file'}
         )
 
     def test_submodule_contents_by_name(self):
         self.assertEqual(
-            names(resources.files('ziptestdata.subdirectory')),
+            names(resources.files('data01.subdirectory')),
             {'__init__.py', 'binary.file'},
         )
 
     def test_as_file_directory(self):
-        with resources.as_file(resources.files('ziptestdata')) as data:
-            assert data.name == 'ziptestdata'
+        with resources.as_file(resources.files('data01')) as data:
+            assert data.name == 'data01'
             assert data.is_dir()
             assert data.joinpath('subdirectory').is_dir()
             assert len(list(data.iterdir()))
@@ -124,7 +118,7 @@ class ResourceFromZipsTest01(util.ZipSetupBase, unittest.TestCase):
 
 
 class ResourceFromZipsTest02(util.ZipSetupBase, unittest.TestCase):
-    ZIP_MODULE = zipdata02  # type: ignore
+    ZIP_MODULE = 'data02'
 
     def test_unrelated_contents(self):
         """
@@ -132,93 +126,48 @@ class ResourceFromZipsTest02(util.ZipSetupBase, unittest.TestCase):
         distinct resources. Ref python/importlib_resources#44.
         """
         self.assertEqual(
-            names(resources.files('ziptestdata.one')),
+            names(resources.files('data02.one')),
             {'__init__.py', 'resource1.txt'},
         )
         self.assertEqual(
-            names(resources.files('ziptestdata.two')),
+            names(resources.files('data02.two')),
             {'__init__.py', 'resource2.txt'},
         )
 
 
-@contextlib.contextmanager
-def zip_on_path(dir):
-    data_path = pathlib.Path(zipdata01.__file__)
-    source_zip_path = data_path.parent.joinpath('ziptestdata.zip')
-    zip_path = pathlib.Path(dir) / f'{uuid.uuid4()}.zip'
-    zip_path.write_bytes(source_zip_path.read_bytes())
-    sys.path.append(str(zip_path))
-    import_module('ziptestdata')
-
-    try:
-        yield
-    finally:
-        with contextlib.suppress(ValueError):
-            sys.path.remove(str(zip_path))
-
-        with contextlib.suppress(KeyError):
-            del sys.path_importer_cache[str(zip_path)]
-            del sys.modules['ziptestdata']
-
-        with contextlib.suppress(OSError):
-            unlink(zip_path)
-
-
-class DeletingZipsTest(unittest.TestCase):
+class DeletingZipsTest(util.ZipSetupBase, unittest.TestCase):
     """Having accessed resources in a zip file should not keep an open
     reference to the zip.
     """
 
-    def setUp(self):
-        self.fixtures = contextlib.ExitStack()
-        self.addCleanup(self.fixtures.close)
-
-        modules = import_helper.modules_setup()
-        self.addCleanup(import_helper.modules_cleanup, *modules)
-
-        temp_dir = self.fixtures.enter_context(os_helper.temp_dir())
-        self.fixtures.enter_context(zip_on_path(temp_dir))
-
     def test_iterdir_does_not_keep_open(self):
-        [item.name for item in resources.files('ziptestdata').iterdir()]
+        [item.name for item in resources.files('data01').iterdir()]
 
     def test_is_file_does_not_keep_open(self):
-        resources.files('ziptestdata').joinpath('binary.file').is_file()
+        resources.files('data01').joinpath('binary.file').is_file()
 
     def test_is_file_failure_does_not_keep_open(self):
-        resources.files('ziptestdata').joinpath('not-present').is_file()
+        resources.files('data01').joinpath('not-present').is_file()
 
     @unittest.skip("Desired but not supported.")
     def test_as_file_does_not_keep_open(self):  # pragma: no cover
-        resources.as_file(resources.files('ziptestdata') / 'binary.file')
+        resources.as_file(resources.files('data01') / 'binary.file')
 
     def test_entered_path_does_not_keep_open(self):
         """
         Mimic what certifi does on import to make its bundle
         available for the process duration.
         """
-        resources.as_file(resources.files('ziptestdata') / 'binary.file').__enter__()
+        resources.as_file(resources.files('data01') / 'binary.file').__enter__()
 
     def test_read_binary_does_not_keep_open(self):
-        resources.files('ziptestdata').joinpath('binary.file').read_bytes()
+        resources.files('data01').joinpath('binary.file').read_bytes()
 
     def test_read_text_does_not_keep_open(self):
-        resources.files('ziptestdata').joinpath('utf-8.file').read_text(
-            encoding='utf-8'
-        )
+        resources.files('data01').joinpath('utf-8.file').read_text(encoding='utf-8')
 
 
-class ResourceFromNamespaceTest01(unittest.TestCase):
-    site_dir = str(pathlib.Path(__file__).parent)
-
-    @classmethod
-    def setUpClass(cls):
-        sys.path.append(cls.site_dir)
-
-    @classmethod
-    def tearDownClass(cls):
-        sys.path.remove(cls.site_dir)
-
+class ResourceFromNamespaceTests:
     def test_is_submodule_resource(self):
         self.assertTrue(
             resources.files(import_module('namespacedata01'))
@@ -237,7 +186,9 @@ class ResourceFromNamespaceTest01(unittest.TestCase):
             contents.remove('__pycache__')
         except KeyError:
             pass
-        self.assertEqual(contents, {'binary.file', 'utf-8.file', 'utf-16.file'})
+        self.assertEqual(
+            contents, {'subdirectory', 'binary.file', 'utf-8.file', 'utf-16.file'}
+        )
 
     def test_submodule_contents_by_name(self):
         contents = names(resources.files('namespacedata01'))
@@ -245,7 +196,45 @@ class ResourceFromNamespaceTest01(unittest.TestCase):
             contents.remove('__pycache__')
         except KeyError:
             pass
-        self.assertEqual(contents, {'binary.file', 'utf-8.file', 'utf-16.file'})
+        self.assertEqual(
+            contents, {'subdirectory', 'binary.file', 'utf-8.file', 'utf-16.file'}
+        )
+
+    def test_submodule_sub_contents(self):
+        contents = names(resources.files(import_module('namespacedata01.subdirectory')))
+        try:
+            contents.remove('__pycache__')
+        except KeyError:
+            pass
+        self.assertEqual(contents, {'binary.file'})
+
+    def test_submodule_sub_contents_by_name(self):
+        contents = names(resources.files('namespacedata01.subdirectory'))
+        try:
+            contents.remove('__pycache__')
+        except KeyError:
+            pass
+        self.assertEqual(contents, {'binary.file'})
+
+
+class ResourceFromNamespaceDiskTests(ResourceFromNamespaceTests, unittest.TestCase):
+    site_dir = str(pathlib.Path(__file__).parent)
+
+    @classmethod
+    def setUpClass(cls):
+        sys.path.append(cls.site_dir)
+
+    @classmethod
+    def tearDownClass(cls):
+        sys.path.remove(cls.site_dir)
+
+
+class ResourceFromNamespaceZipTests(
+    util.ZipSetupBase,
+    ResourceFromNamespaceTests,
+    unittest.TestCase,
+):
+    ZIP_MODULE = 'namespacedata01'
 
 
 if __name__ == '__main__':
diff --git a/lib/importlib_resources/tests/update-zips.py b/lib/importlib_resources/tests/update-zips.py
deleted file mode 100644
index 231334aa..00000000
--- a/lib/importlib_resources/tests/update-zips.py
+++ /dev/null
@@ -1,53 +0,0 @@
-"""
-Generate the zip test data files.
-
-Run to build the tests/zipdataNN/ziptestdata.zip files from
-files in tests/dataNN.
-
-Replaces the file with the working copy, but does commit anything
-to the source repo.
-"""
-
-import contextlib
-import os
-import pathlib
-import zipfile
-
-
-def main():
-    """
-    >>> from unittest import mock
-    >>> monkeypatch = getfixture('monkeypatch')
-    >>> monkeypatch.setattr(zipfile, 'ZipFile', mock.MagicMock())
-    >>> print(); main()  # print workaround for bpo-32509
-    <BLANKLINE>
-    ...data01... -> ziptestdata/...
-    ...
-    ...data02... -> ziptestdata/...
-    ...
-    """
-    suffixes = '01', '02'
-    tuple(map(generate, suffixes))
-
-
-def generate(suffix):
-    root = pathlib.Path(__file__).parent.relative_to(os.getcwd())
-    zfpath = root / f'zipdata{suffix}/ziptestdata.zip'
-    with zipfile.ZipFile(zfpath, 'w') as zf:
-        for src, rel in walk(root / f'data{suffix}'):
-            dst = 'ziptestdata' / pathlib.PurePosixPath(rel.as_posix())
-            print(src, '->', dst)
-            zf.write(src, dst)
-
-
-def walk(datapath):
-    for dirpath, dirnames, filenames in os.walk(datapath):
-        with contextlib.suppress(ValueError):
-            dirnames.remove('__pycache__')
-        for filename in filenames:
-            res = pathlib.Path(dirpath) / filename
-            rel = res.relative_to(datapath)
-            yield res, rel
-
-
-__name__ == '__main__' and main()
diff --git a/lib/importlib_resources/tests/util.py b/lib/importlib_resources/tests/util.py
index ce0e6fad..fb827d2f 100644
--- a/lib/importlib_resources/tests/util.py
+++ b/lib/importlib_resources/tests/util.py
@@ -4,11 +4,12 @@ import io
 import sys
 import types
 import pathlib
+import contextlib
 
 from . import data01
-from . import zipdata01
 from ..abc import ResourceReader
-from ._compat import import_helper
+from .compat.py39 import import_helper, os_helper
+from . import zip as zip_
 
 
 from importlib.machinery import ModuleSpec
@@ -141,39 +142,23 @@ class CommonTests(metaclass=abc.ABCMeta):
 
 
 class ZipSetupBase:
-    ZIP_MODULE = None
-
-    @classmethod
-    def setUpClass(cls):
-        data_path = pathlib.Path(cls.ZIP_MODULE.__file__)
-        data_dir = data_path.parent
-        cls._zip_path = str(data_dir / 'ziptestdata.zip')
-        sys.path.append(cls._zip_path)
-        cls.data = importlib.import_module('ziptestdata')
-
-    @classmethod
-    def tearDownClass(cls):
-        try:
-            sys.path.remove(cls._zip_path)
-        except ValueError:
-            pass
-
-        try:
-            del sys.path_importer_cache[cls._zip_path]
-            del sys.modules[cls.data.__name__]
-        except KeyError:
-            pass
-
-        try:
-            del cls.data
-            del cls._zip_path
-        except AttributeError:
-            pass
+    ZIP_MODULE = 'data01'
 
     def setUp(self):
-        modules = import_helper.modules_setup()
-        self.addCleanup(import_helper.modules_cleanup, *modules)
+        self.fixtures = contextlib.ExitStack()
+        self.addCleanup(self.fixtures.close)
+
+        self.fixtures.enter_context(import_helper.isolated_modules())
+
+        temp_dir = self.fixtures.enter_context(os_helper.temp_dir())
+        modules = pathlib.Path(temp_dir) / 'zipped modules.zip'
+        src_path = pathlib.Path(__file__).parent.joinpath(self.ZIP_MODULE)
+        self.fixtures.enter_context(
+            import_helper.DirsOnSysPath(str(zip_.make_zip_file(src_path, modules)))
+        )
+
+        self.data = importlib.import_module(self.ZIP_MODULE)
 
 
 class ZipSetup(ZipSetupBase):
-    ZIP_MODULE = zipdata01  # type: ignore
+    pass
diff --git a/lib/importlib_resources/tests/zip.py b/lib/importlib_resources/tests/zip.py
new file mode 100644
index 00000000..962195a9
--- /dev/null
+++ b/lib/importlib_resources/tests/zip.py
@@ -0,0 +1,32 @@
+"""
+Generate zip test data files.
+"""
+
+import contextlib
+import os
+import pathlib
+import zipfile
+
+import zipp
+
+
+def make_zip_file(src, dst):
+    """
+    Zip the files in src into a new zipfile at dst.
+    """
+    with zipfile.ZipFile(dst, 'w') as zf:
+        for src_path, rel in walk(src):
+            dst_name = src.name / pathlib.PurePosixPath(rel.as_posix())
+            zf.write(src_path, dst_name)
+        zipp.CompleteDirs.inject(zf)
+    return dst
+
+
+def walk(datapath):
+    for dirpath, dirnames, filenames in os.walk(datapath):
+        with contextlib.suppress(ValueError):
+            dirnames.remove('__pycache__')
+        for filename in filenames:
+            res = pathlib.Path(dirpath) / filename
+            rel = res.relative_to(datapath)
+            yield res, rel
diff --git a/lib/importlib_resources/tests/zipdata01/ziptestdata.zip b/lib/importlib_resources/tests/zipdata01/ziptestdata.zip
deleted file mode 100644
index 9a3bb073..00000000
Binary files a/lib/importlib_resources/tests/zipdata01/ziptestdata.zip and /dev/null differ
diff --git a/lib/importlib_resources/tests/zipdata02/ziptestdata.zip b/lib/importlib_resources/tests/zipdata02/ziptestdata.zip
deleted file mode 100644
index d63ff512..00000000
Binary files a/lib/importlib_resources/tests/zipdata02/ziptestdata.zip and /dev/null differ
diff --git a/package/requirements-package.txt b/package/requirements-package.txt
index f1ad724e..fd444e98 100644
--- a/package/requirements-package.txt
+++ b/package/requirements-package.txt
@@ -1,6 +1,6 @@
 apscheduler==3.10.1
 importlib-metadata==6.8.0
-importlib-resources==6.0.1
+importlib-resources==6.4.0
 pyinstaller==6.4.0
 pyopenssl==24.0.0
 pycryptodomex==3.20.0
diff --git a/requirements.txt b/requirements.txt
index a91534d0..ad20a775 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -19,7 +19,7 @@ html5lib==1.1
 httpagentparser==1.9.5
 idna==3.4
 importlib-metadata==6.8.0
-importlib-resources==6.0.1
+importlib-resources==6.4.0
 git+https://github.com/Tautulli/ipwhois.git@master#egg=ipwhois
 IPy==1.01
 Mako==1.3.2